21. Which has the least gravitational potential energy-a 5 kg ball that is 3 meters high or a 3 kg ball that is 3 meters high?

Sort the images based on whether there's a force of attraction or repulsion between the magnets shown. attraction repulsion

In a classical model of the hydrogen atom, the electron moves around the proton in a circular orbit of radius 0.053 nm. what is the electron's orbital frequency? what is the effective current of the electron?

Alarge cruise ship of mass 7.00 ✕ 107 kg has a speed of 11.6 m/s at some instant. (a) what is the ship's kinetic energy at this time? (b) how much work is required to stop it? (give the work done on the ship. include the sign of the value in your answer.) (c) what is the magnitude of the constant force required to stop it as it undergoes a displacement of 3.00 km?